Reaction temperature affects the formation of clinkers. You can use exhaust gas recirculation to help keep the reaction temperature below 1100C where ashes begin to vitrify.
Also see Don’s grate and clean-out solution: Don's Geo Tracker Project - 2- - Charcoal - #131 by don_mannes
If that link doesn’t work go to Don’s Geo Tracker Project - 2-- Charcoal, entry 131